Modern vehicles typically have a vehicle diagnostic system, typically having one or more separate computer control modules. Examples of such computer control modules (also known as just “modules”) are: a powertrain control module (PCM), an engine control module (ECM), a transmission control module (TCM), an ABS control module, and an air bag control module.
“Off-board devices,” such as scan tools, are known in the art and are testing devices that interface with vehicle diagnostic systems to, e.g., access, display, and/or print vehicle diagnostic information. OBD II (On-Board Diagnostics version II) Scan Tools are one commonly known type of scan tool and are governed by a number of standards, e.g., SAE J1978 Rev. 1998-02 and SAE J1979 Rev. 1997-09. Scan tools are relatively expensive diagnostic devices that have a relatively large number of features and are typically marketed to professional automobile mechanics and service stations. Scan tools are generally considered to be beyond the means of most automobile hobbyists and the ordinary individual interested in performing simple maintenance or service of a few vehicles, such as a family “fleet” of vehicles.
There are different types of scan tools. An “OBD II Scan Tool” complies with the above-identified specifications. By contrast, a “Manufacturer-Specific Scan Tool” is a scan tool that accesses and displays proprietary manufacturer-specific data (and possibly also additionally accesses and displays OBD II data). Examples include Device Controls on General Motors, On-Demand Tests in Ford, Actuator Tests, Sensor Tests, Interrogator, Read Temporary Codes in Chrysler. In general, air bag data, ABS data, cruise control data, and climate control data are also considered to be proprietary manufacturer-specific data and are typically included only in Manufacturer-Specific Scan Tools.
Another “off-board device” that is a low-cost alternative to the scan tool is a “code reader.” In 1998 Actron Manufacturing Corp., the assignee of the present invention, pioneered the first OBD II code reader. In contrast with a scan tool, a code reader is a relatively basic “off-board device” that links with one or more computer modules in a vehicle diagnostic system via a vehicle computer network, reads any diagnostic trouble codes (also referred to as just “diagnostic codes” herein) asserted by those vehicle diagnostic systems, and displays any diagnostic codes on a display. Typical code readers do not perform the following major functions that are performed by typical scan tools: “View Data,” also known as “Live Data,” “Data,” and “Data Test, DTC” (viewing and displaying in real-time live, changing data from a plurality of module sensors), display of textual diagnosis descriptions corresponding to the various diagnostic codes, recording and playback of data, device control (manually controlling modules for diagnostic purposes), and reading and displaying vehicle information from the vehicle's computer (e.g., VIN information, controller calibration identification number, etc.). Code readers are typically marketed to automobile hobbyists and non-professionals who are merely curious about what codes the various vehicle diagnostic systems have stored in their memories.
As used here, an “OBD II Scan Tool” is significantly different from a manufacturer-specific “scan tool.” A given off-board device might be a scan tool but not an OBD II Scan Tool, because it does not meet applicable specifications. Also, as used herein, a “scan tool” is significantly different from a “code reader.” The “live data” function, i.e., the ability to view and display real-time live data from a plurality of various different sensors (and other information derived from sensor data) is a very important feature of scan tools, and can be used to distinguish a scan tool from a code reader. Thus, as used herein, the term “scan tool” means an off-board device that (a) obtains and displays vehicle diagnostic trouble codes (preferably but not necessarily OBD II DTCs) from a vehicle diagnostic system and (b) obtains and displays in real-time live, changing vehicle diagnostic data from a plurality of modules representing either (i) sensor data or (ii) information derived from sensor data. Similarly, as used herein, the term “code reader” means an off-board device that (a) does obtain and display vehicle diagnostic trouble codes (preferably but not necessarily OBD II DTCs) from a vehicle diagnostic system and (b) does not obtain and display in real-time live, changing vehicle diagnostic data from a plurality of modules representing either (i) sensor data or (ii) information derived from sensor data. By way of example, but not of limitation, examples of sensor data and information derived from sensor data are (1) calculated load value (e.g., SAE J1979 9/97 PID 04H), (2) engine coolant temperature (e.g., PID 05H), (3) engine RPM (e.g., PID 0CH), (4) absolute throttle position (e.g., PID 11H), (5) intake air temperature (PID 0FH), and (6) oxygen sensor data (e.g., at least one of PID 14H through 1BH). The reading and display of malfunction indicator light (MIL) status, even if obtained and displayed live, in real-time, would not be considered to be “live data” and would not, by itself, make an off-board device be considered to be a scan tool, because illumination of MIL indicates that there is a code available in on of the modules and does not represent either (i) sensor data or (ii) information derived from sensor data. By way of further example, on the one hand an off-board device that obtains and displays vehicle diagnostic trouble codes from a vehicle diagnostic system and that obtains and displays in real-time live, changing vehicle diagnostic data representing one or more of the six above-listed parameters (or other data representing sensor data or information derived from sensor data) is a scan tool. On the other hand, an off-board device that obtains and displays vehicle diagnostic trouble codes from a vehicle diagnostic system and that does not obtain and display in real-time live, changing vehicle diagnostic data representing one or more of the six above-listed parameters (or other data representing sensor data or information derived from sensor data) is a code reader and not a scan tool, even if it displays MIL status.
One typically uses a code reader when a vehicle malfunction indicator light (“MIL”) (e.g., the “Check Engine” light) on the dashboard of a vehicle is illuminated. In response to the illumination of such a light, e.g., a “Check Engine” display, the user connects an code reader to the vehicle diagnostic connector, presses a first button (e.g., a READ or LINK button) or activates a menu-driven function, which causes the code reader to (i) establish communications with the various modules in a vehicle diagnostic system using a communications protocol, (ii) read any codes which are stored in the vehicle's computer modules in the vehicle diagnostic system, and (iii) display one or more vehicle diagnostic codes via a display. The user then uses a reference manual to determine the nature of the diagnosis corresponding to each diagnostic code.
For example, the ACTRON® CP9035 code reader, generally recognized as the first OBDII code reader, has three buttons, a READ button, an ERASE button, and an arrow button, four LEDs, labeled “Power Train,” “Body,” “Chassis,” and “Uart,” and a four-digit seven-segment LED numeric display. When an indicator light is illuminated, or just to see if any diagnostic codes are available, a user will connect the connector of the code reader to the connector for the vehicle diagnostic system network. The CP9035 code reader is powered by the vehicle being tested. The user initiates the link and read process by pressing the READ button, which causes the CP9035 to (i) establish communications with vehicle computer modules in the vehicle diagnostic system using a communications protocol, (ii) read any codes which are stored in vehicles computer modules in the vehicle diagnostic system, and (iii) display the first vehicle diagnostic code via an LED and the numeric display. The other codes are displayed in turn by pressing the arrow button. The codes are erased by pressing the ERASE button.
Although scan tools display OBD II and/or manufacturer-specific textual diagnosis descriptions, with the much simpler code readers, the user must manually determine the nature of the codes. For example, if five codes are displayed 0743, 0443, 0118, 0113, and 1490, all with the “Power Train” LED illuminated, then the user would understand that the CP9035 code reader had read the following codes from the vehicle diagostic system: P0743, P0443, P0118, P0113, and P1490. In response, the user would open the manual, and read the corresponding descriptions. Relevant portions of the manual read:
P0113Intake Air Temperature Circuit High PointP0118Engine Coolant Temperature Circuit High InputP0443Evaporative Emission Control System PurgeControl Valve Circuit MalfunctionP0743Torque Converter Clutch Circuit ElectricalP1490Low Speed Fan Control Relay Circuitallowing the user to manually determine the respective diagnosis corresponding to each diagnostic code. This process of manually reading the OBD II and/or manufacturer-specific textual diagnosis descriptions can be time-consuming and, of course, is subject to human error.
Thus, although code readers provide an inexpensive way to permit one to read OBD II and/or manufacturer-specific codes from vehicle diagnostic systems, there is a need for an improved code reader.